09/451/011-Nov. 29, 1999.
Not Applicable.
Not Applicable.
(1) Field of the Invention
This invention relates to adult bicycles using small wheels only specifically to an improved bicycle frame having single tube chainstay and seatstay that are not attached to the rear wheel axle.
(2) Description of the Related Art
Generally, bicycles for adults have big wheels. The chainstay and the seatstay are both made of smaller tubes than the rest of the frame, forming a fork to accommodate the rear wheel, and the drop tips attached to the rear wheel axle. Both chainstay and seatstay are considered as the weakest part of the frame. The chainstay is positioned in an almost horizontal position so that almost all of the vertical component of the load is being supported by the rear wheel. The big wheels are difficult to turn. These two factors make it difficult to push the pedal.
Bicycles for adults may be classified into 3 types depending on how many gears are there in the transmission system. They are: Type 1 has only two gears, the chainwheel and the rear wheel gear. The chainwheel is the large gear while the rear wheel gear is the small gear. A chain connects the two together. This large/small gear combination makes the rear wheel turn faster. If there are multiple gears at the rear wheel, only the smallest counts because the other gears which are larger slow down the rotation of the wheel. Type 2 has the basic chainwheel and small rear wheel gear plus an additional shaft attached with a small/large gear combination, is interposed between the chainwheel and the rear wheel gear. Two chains interconnect all the gears. The first chain connects the chainwheel to the small gear of the added gear combination, while a second chain connects the large gear to the rear wheel gear. Type 3 has the basic chainwheel and rear wheel gear plus an additional two shafts each with a small/large gear combination, interposed between the chainwheel and the rear wheel gear. Three separate chains interconnect all the gears. A first chain connects the chainwheel to the first small gear of the first added gear combination, a second chain connects the first large gear added, to the second small gear of the added combination, and a third chain connects the second large gear added in the combination, to the rear wheel gear.
Some examples of the type 2 bicycles are: U.S. Pat. No. 1,154,292-Sep. 19, 1915 Cribbs; U.S. Pat. No. 1,360,032-Nov. 19, 1920 Schiffner; U.S. Pat. No. 1,535,714-Apr. 19, 1925 Burke. An example of a type 3 bicycle is U.S. Pat. No. 5,913,741-Jun. 22, 1999 Balajadia.
Another relevant prior art is application 09/451/011 filed on Nov. 29, 1999, entitled Rear Wheel Assembly. The purpose of the invention is to lighten pedal pushing of bicycles. It utilizes 3 principles in order to achieve this. First is the use of more than one wheel in order to distribute the load carried by the wheels; second, slanting the fork of the wheels at 45xc2x0 in order to reduce the vertical component of the load, and third, using small size wheels only in order to reduce the resistance of the wheel to rotate. Utilizing one or more of these principles will help lessen the effort needed to push the pedals.
The improved bicycle frame is made with single tubes only, resulting in a stronger, sturdier, and more stable structure. It is designed for adult bicycles using small wheels only, i.e. diameters of less than half of the big wheels in use today. A bicycle with the improved frame is lighter to pedal.